Neuropeptide Y (NPY) has recently been identified in diverse sites in the rat brain. Our studies show that NPY stimulates feeding in rats. The major objectives of this proposal are to understand further where and how NPY acts in the brain to modulate feeding and drinking behavior. Experiments are designed to determine a dose response effect of NPY, identify the specific central sites of NPY action and elucidate the interplay between NPY and adrenergic neurons. The major techniques are: intraventricular and intracerebral injection or infusion of NPY, adrenalectomy, hypophysectomy and use of pharmacologic drugs which block neurotransmitter synthesis or adrenergic receptors. It is hoped that these investigations will further our understanding of the central control of ingestive behavior in rats.